From legacy to Web through interaction modeling

In the context of the CelLEST project, we have been investigating the problem of reengineering and reusing the services provided by legacy applications, running on mainframe hosts. This work has resulted in a suite of methods, based on understanding and modeling the users' interaction with the legacy-application interface. These methods aim at (a) modeling the behavior of the legacy user interface as a state-transition diagram, (b) recovering specifications for the application's functions by discovering the users' tasks as frequently occurring interaction patterns, and (c) constructing new user-interface front-ends to make the recovered legacy functions accessible through the Web. We describe the overall process for legacy migration to the World Wide Web, using the CelLEST methods, and we illustrate it with an example case study.